Joining us now to talk about what the U.S. hopes to accomplish at the UN climate talks in Durban is the chief negotiator for the United States, Todd Stern. He's been negotiating on behalf of the U.S. off and on since the Kyoto Protocol was first forged back in 1997. Todd Stern, welcome to the program.

TODD STERN: Thanks very much, Guy. Happy to be here.

RAZ: As we just heard, the expectations are pretty low for a treaty that limits emissions coming out of Durban. What needs to happen at Durban for you to consider it a success?

STERN: Well, look, I think what people need to understand is that what happened last year in Cancun was really quite a significant agreement. For the first time, all major economies agreed to limit their emissions in quite specific ways, to submit those actions to a regime of international transparency where the principles were agreed last year. There was an agreement to set up a green climate fund, to set up a technology center and network and so forth. So, a lot of agreements that were made, if you will, in principle that need to be implemented, that need to be made operational.

But the conditions were not right yet and I think they're probably still not right for a legally binding agreement that's going to be legally binding on all the major players. We're not there yet.

RAZ: You do - so basically, you do not expect a legally binding treaty to come out of Durban.

STERN: There's not going to be a legally binding treaty coming out of Durban because, again, we - the United States made a submission for a legally binding agreement in April of 2009, but that was a submission that was based on all the major players, not just the developed countries, but China and India and Brazil and other big players, all being bound in a common agreement. Those countries are not prepared to do that at this point. I don't say that critically.

I think they - everybody's got their own interest. But if they're not prepared to do those things yet, then we are not prepared to go forward on the basis of the old-style agreement, which essentially had a firewall between all developed countries and all developing countries. After all, China, at this point, is the largest emitter in the world. Developing countries are 55 percent of global emissions now. They'll be 65 percent by 2030. So, to set up an agreement on the basis of an old 1992 division between developed and developing countries doesn't work, doesn't make sense substantively.

RAZ: In other words, China and India should not be excluded from any treaty.

STERN: That's right. Correct.

RAZ: You say the time is not ripe. Do you mean it's not ripe because of political circumstances in the developed world or the global economy or both?

STERN: Well, no. All I mean by that is that in order to - for the time to be right, all the major players have to be prepared to be legally bound in essentially the same way. And that - we're not there right now.

RAZ: Countries at these talks, they agree that global warming should be limited to a rise of no more than two degrees Celsius, period. But the political agreements on the table aren't nearly enough to prevent that from happening. How do you reconcile what science says and what seems to be politically possible?

STERN: You know, it's a good question and that's always a challenge. I think all you can ever do is try to push as far as we can and to recognize that politics is the art of the possible. I think that if you look at the pledges that were made and embedded into the Cancun agreement, you will see, by far, more emission reductions and greater movement toward that two degree goal than ever before. And nobody's taking those pledges lightly. Not China, not Brazil, not India, not the United States or Europe.

Is it enough to get to two degrees? Probably not, but it's a good start on the way to 2020. There's a heck of a lot more that's going to have done after that.

RAZ: Todd, Stern, let me ask you about what you experience when you go to these climate conferences. Among other things, we are the only major country in the world that is still debating whether or not climate change is real. Do people ask you when you go to these conferences, you know, where is U.S. leadership on this issue?

STERN: I don't think they ask so much where U.S. leadership is because I think people have seen President Obama in action. But I think people are quite befuddled by what they see in the U.S., in terms of the level of skepticism and even denial of basic science. Global warming is happening, humans are clearly contributing factors, and we have to act to control it. I think most people understand that.

There has been, you know, a cottage industry of people who try to dispute those facts, which is not constructive. And I do think people around the world are confused by it.

RAZ: Todd Stern, thank you.

STERN: Thanks.

RAZ: Todd Stern is the chief U.S. envoy to the U.N climate talks happening in Durban, South Africa this week. Transcript provided by NPR, Copyright NPR.